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Unit 4 – Earth Forces
Science 10
Unit 4 - Earth Science
Chapters 12 and 13 in your text book. We will not be following the text
exactly.
http://www.enchantedlearning.com/subjects/astronomy/planets/earth/index.shtml
Unit 4.1.1 – Layers of the Earth
The Layers of the Earth
1. The Crust – the outer layer, 10km – 70km thick, composed of
silicon and oxygen
2. The Mantle – underneath the crust – 2900km thick, most dense
because it consists of iron and magnesium
The upper mantle and crust – collectively called the
lithosphere ~ 100 km thick
Plastic like layer below the lithosphere is the asthenosphere
Plates “float” on the asthenosphere – this layer is similar to
melted tar.
Science 10
Unit 4 – Earth Forces
3. Outer core – 2100 km thick, composed of molten iron and nickel
4. Inner core – solid ball of iron and nickel, radius is 1300km
There are 12 major plates and several smaller plates that make up the earth
surface.
http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Inside.s
html
http://scign.jpl.nasa.gov/learn/plate1.htm
Rocks and structures
There are 3 main groups of rocks
1. Igneous
2. Sedimentary
3. Metamorphic
1. Igneous
- were once hot liquids inside the earth crust.
- Magma – is molten rock
- Lava – magma that flows out of the earth to the surface
- Ash – lava that is blown out of a volcano
i.
Volcanic Rocks
Ex; basalt, obsidian, and pumice
ii. Plutonic rocks
1. magma that has cooled beneath the surface
ex; Granite
2. Sedimentary
- Consists of rock fragments (sand, mud, gravel) that has
been cemented together
- Weathering – physical or chemical breakdown by wind,
water or ice
Unit 4 – Earth Forces
Science 10
- Sediment – fragments that are transported by rivers or
streams that settle on the sea floor in layers
1. mudstone from mud
2. shale from clay
3. sandstone from sand
4. conglomerate from gravel
- Fossils – plant or animal remain that have been buried
5. Limestone – from fossil fragment
3. Metamorphic
- Igneous or metamorphic rocks that have been changed by
heat and pressure
- Ex; mudstone or shale into slate
- Ex; limestone into marble
Quick Check
1. All of the layers of the earth are made up of solid rock
True
False
2. The thickest layer if the earth is the mantle
True
False
3. The inner core is made of liquid iron and nickel
True
False
True
False
True
False
4. During the initial cooling of the earth lighter elements
floated to the surface to form a thin crust
5. The outer core is composed of silicon and oxygen
Hand out pg 226 review questions
Science 10
Unit 4 – Earth Forces
Unit 4.1.2 – Techniques for Observing the Earths Surface
Geologist – scientists who study the earth
How do we know how old the earth is?
Scientists study the “changes”
change in volume…ex; trees, rivers, crystals
change in layers…rock layers under a river on a mountain
side or in a canyon
Geological Field Work –
Drilling –
Remote Sensing –
Handout page 229
Unit 4 – Earth Forces
Science 10
Unit 4 - Earth Science
Chapters 12 and 13 in your text book. We will not be following the text exactly.
Unit 4.1.1 – Layers of the Earth
The Layers of the Earth
1. The ___________ – the ___________layer, 10km – 70km thick, composed of
_________ and _________
2. The _________ – underneath the crust – _________ thick, most _________ because
it consists of _________ and _________
The upper mantle and crust – collectively called the _____________ ~ 100 km thick
Plastic like layer below the lithosphere is the __________________
Plates “float” on
the asthenosphere – this layer is similar to melted tar.
3.______________– 2100 km thick, composed of molten _________ and
_________
4. ______________– solid ball of _________ and _________l, radius is 1300km
There are 12 major plates and several smaller plates that make up the earth surface.
Unit 4 – Earth Forces
Science 10
Rocks and structures
There are 3 main groups of rocks
1. Igneous
2. Sedimentary
3. Metamorphic
1. Igneous
- were ___________________________inside the earth crust.
-
_________ – is molten rock
-
_________ – magma that _________ out of the earth to the surface
-
_________ – lava that is _________ out of a volcano
i.
Volcanic Rocks
Ex; _________, _________, and _________
ii.
Plutonic rocks
1. magma that has cooled beneath the surface
ex; _________
2. Sedimentary
-
Consists of rock _____________ (sand, mud, gravel) that has been cemented
together
-
Weathering – _________ or _________l breakdown by wind, water or ice
-
_________ – fragments that are _________ by rivers or streams that settle
on the sea floor in layers
1. _________ from mud
2. _________ from clay
3. _________e from sand
4. _________ from gravel
-
Fossils – plant or animal remain that have been buried
5. _________ – from fossil fragment
3.Metamorphic
a. Igneous or metamorphic rocks that have been changed by heat and pressure
b. Ex; mudstone or shale into _________
c. Ex; limestone into _________
Unit 4 – Earth Forces
Science 10
Quick Check
1. All of the layers of the earth are made up of solid rock
True
False
2. The thickest layer if the earth is the mantle
True
False
3. The inner core is made of liquid iron and nickel
True
False
True
False
True
False
4. During the initial cooling of the earth lighter elements
floated to the surface to form a thin crust
5. The outer core is composed of silicon and oxygen
Unit 4.1.2 – Techniques for Observing the Earths Surface
_________– scientists who study the earth
How do we know how old the earth is?
Scientists study the “changes”
change in volume…ex; trees, rivers, crystals
change in layers…rock layers under a river on a mountain
side or in a canyon
Geological Field Work –
Drilling –
Remote Sensing –
Science 10
Unit 4 – Earth Forces
Unit 4.1.3 - Analyzing the Earth’s Interior
Seismology – the study of earthquakes and their effects
Earthquakes
Alaska, 1964 - one of the most violent quakes of recent times.
- It lasted 7 minutes
- It was felt in Texas
- The ground moved up and down 6m
- A giant ocean wave was set off 200km away, which rushed to shore
and moved a 10 000 tonne ship on to land.
Earthquakes occur along faults. The rock can move vertically or
horizontally. The force of the moving plates cause rocks to bend
stretch and break.
An earthquake is the vibrations produced by breaking rock at a
fault.
An earthquake occurs when the friction of the rock temporarily halts
their movement at a fault.
The forces are still applied to the rock building up stress at the points
where the rock is stuck. The rock is bent and stretched.
The earth has been storing energy as it bends this is called
potential energy.
Eventually it is bent beyond its elastic limit and it breaks. As soon as
the earth breaks, it releases energy as it moves, this is called Kinetic
Energy.
Use wooden splints as examples
The energy is released in the form of seismic waves.
Science 10
Unit 4 – Earth Forces
The point where energy is released (as
rocks move past each other at a fault)
is called the focus of the earthquake.
Usually within 10 to 65 km of the
Earth’s surface.
Epicenter – is the point on the
Earth’s surface directly above the
earthquake focus.
During an earthquake
- the ground can become a wave of up to 2 m high
- the vibrations can cause the soil to liquefy because water is
vibrated to the surface and create a tidal wave of rock and
mud. This process is called liquefaction
If an earth quake occurs under the ocean. A tsunami is formed. A
tsunami is a giant wave that can travel 800km/h, and reach a height
of 70m.
- It starts out as a ripple on the ocean surface and gets taller as it
approaches shore.
Aftershocks – the unstable ground can shift and settle after an
earthquake. This can last for months.
Science 10
Unit 4 – Earth Forces
This pictures shows the location of the major earthquakes in the last
15 years – Most earthquakes occur along plate boundaries.
Measuring Earthquakes
Seismogram or seismometer- is a device used to measure
seismic waves.
Consists of a rotating drum of paper and a pen on a
pendulum
Earthquakes cause the drum to vibrate
while the pen stays at rest.
A paper record of seismic waves is a
seismograph
The seismogram can measure the amplitude and
intensity of the vibrations. They are VERY
sensitive and can magnify the vibration by 100 000 times.
Science 10
Unit 4 – Earth Forces
Comparing Earthquakes
1. Mercalli Scale
- it is based on the assessment of damage caused by the quake.
Level 1 = quake not felt
Level 3 = light truck passing by
Level 10 = bridges collapse, landslides
Level 12 = Rocks and object are thrown into the air
It is very subjective. It is possible for the same earthquake to affect different
cities very differently.
If the city is built on soft rock, then the city will be damaged.
If the city is built on strong, solid rock then there will be no damage.
2. The Richter Scale
measures the magnitude of the vibrations
- starts at zero and has no upper limit but scientists believe that a 9.5
is maximum strength an earthquake would register.
- Each level is 10X MORE intense than the previous
Example;
-
A quake at 5 on the Richter scale
is 10X more powerful than a quake at 4.
is 100X more powerful than a quake at 3.
is 1000X more powerful than a quake at 2.
Each 10fold increase of the vibrations is 30X more energy
A quake at 5 on the Richter scale
is 30X more powerful than a quake at 4.
is 900X more powerful than a quake at 3.
is 27000X more powerful than a quake at 2.
Unit 4 – Earth Forces
Science 10
Descriptor
Micro
Very
minor
Minor
Light
Moderate
Strong
Major
Great
Richter
Magnitudes
Average
Annually
About 8,000
Less than 2.0 Microearthquakes, not felt.
per day
About 1,000
2.0-2.9
Generally not felt, but recorded.
per day
49,000
3.0-3.9
Often felt, but rarely causes damage.
(estimated)
Noticeable shaking of indoor items,
6,200
4.0-4.9
rattling noises. Significant damage
(estimated)
unlikely.
Can cause major damage to poorly
constructed buildings over small
5.0-5.9
800
regions. At most slight damage to
well-designed buildings.
Can be destructive in areas up to
6.0-6.9
about 100 miles across in populated 120
areas.
Can cause serious damage over larger
7.0-7.9
18
areas.
Can cause serious damage in areas
8.0 or greater
1
several hundred miles across.
Earthquake Effects
Unit 4 – Earth Forces
Science 10
Earthquake Waves
Seismic Waves – are waves of energy that travel through the
earth after an earthquake
The ground can move up and down and can shift from
side to side.
When an earthquake occurs 3 different types of waves are
produced (all at the same time).
1. Primary waves (P waves) – cause particles in the
rocks to move back and forth in the same direction.
- Fastest type of wave, 6 km/sec
ie; waves in a spring
Science 10
Unit 4 – Earth Forces
2. Secondary waves (S waves) – cause rocks to move
in right angles to the direction of the wave, 3.5
km/sec
ie; waves in a rope
3. Love waves or surface waves ( L waves) – rock
particles move in a rolling motion. Likes ripples in a
pond. Slowest type of wave
Draw the rolling on the board
Scientists have learned to use the different speeds of the waves
to calculate the location of the epicenter.
Each type of seismic wave reaches a
seismograph station at a different time
based upon it speed.
If seismic waves reach 3 or more
stations the epicenter can be
determined.
Science 10
Unit 4 – Earth Forces
This is done by using the difference in arrival time between P
and S waves.
Science 10
Unit 4 – Earth Forces
Refraction – the bending of energy waves through different
layers.
Day 1
-
power point notes
Find the Epicenter Activity on power point
notes
Video – Bill Nye – Spinning Things and Earth quakes ( start at 24 min) 25 min VT531.113
S754
-
Handout pg 231 – 233
Video – National Geographic – When the earth quakes (30 min) KT 551.D9972
Day 2
Unit 4 – Earth Forces
Science 10
Unit 4.1.3 - Analyzing the Earth’s Interior
Seismology – the study of earthquakes and their effects
Earthquakes
Alaska, 1964 - one of the most violent quakes of recent times.
- It lasted 7 minutes
- It was felt in Texas
- The ground moved up and down 6m
- A giant ocean wave was set off 200km away, which rushed to shore and
moved a 10,000 tonne ship on to land.
Earthquakes occur along _______________. The rock can move vertically or horizontally.
The force of the moving plates cause rocks to bend ____________ and ____________.
An earthquake is the vibrations produced by breaking rock at a fault.
An earthquake occurs when the ____________ of the rock temporarily halts their
movement at a fault.
The forces are still applied to the rock building up ____________ at the points where the
rock is stuck. The rock is bent and stretched
The earth has been storing energy as it bends this is called _____________energy.
Eventually is bent beyond its elastic limit and it breaks. As soon as the earth breaks, it
releases the energy as it moves, this is called ____________ Energy.
The energy is released in the form of _____________ waves.
The point where energy is released (as rocks move past
each other at a fault) is called the ________ of the
earthquake.
Usually within _____ to _____ km of the Earth’s
surface
____________ – is the point on the Earth’s surface
directly above the earthquake focus.
Science 10
Unit 4 – Earth Forces
During an earthquake
- the ground can become a wave of up to 2 m high
- the vibrations can cause the soil to ____________ because water is vibrated to
the surface and create a tidal wave of rock and mud. This process is called
__________________ .
If an earth quake occurs under the ocean. A _____________ is formed. A tsunami is a
giant wave that can travel 800km/h and be and reach a height of 70m.
- It starts out as a ripple on the ocean surface and gets taller as it approaches shore.
_____________ – the ____________ ground can shift and settle after an earthquake.
This can last for months.
This pictures shows the location of the major earthquakes in the last 15 years – Most
earthquakes occur along plate boundaries.
Measuring Earthquakes
________________ - is a device used to measure seismic
waves.
Consist of a rotating drum of paper and a pen on a
pendulum
Earthquake causes the drum to ____________
while the pen stays at rest.
Paper record of seismic waves is a
______________
Science 10
Unit 4 – Earth Forces
The seismogram can measure the ____________ and ____________ of the
____________. They are VERY sensitive and can magnify the vibration by 100 000 times.
Comparing Earthquakes
1. ________________
- it is based on the assessment of damage caused by the quake.
Level 1 = quake not felt
Level 3 = light truck passing by
Level 10 = bridges collapse, landslides
Level 12 = Rocks and object are thrown into the air
It is very subjective. It is possible for the same earthquake to affect different cities very
differently.
If the city is built on soft rock, then the city will be damaged.
If the city is built on strong, solid rock then there will be no damage.
2. ________________________
- measures the magnitude of the vibrations
- starts at zero and has no upper limit but scientists believe that a 9.5 is maximum
strength an earthquake would register.
- Each level is 10X MORE intense than the previous
Example;
A quake at 5 on the Richter scale
is 10X more powerful than a quake at 4.
is ____X more powerful than a quake at ____.
is ______X more powerful than a quake at ____.
Each 10fold increase of the vibrations is 30X more energy
A quake at 5 on the Richter scale
is 30X more powerful than a quake at 4.
is ________X more powerful than a quake at ____.
is ________X more powerful than a quake at ____.
Science 10
Unit 4 – Earth Forces
Earthquake Waves
Seismic Waves – are waves of energy that travel through the earth after an earthquake
The ground can move up and down and can shift from side to side.
When an earthquake occurs 3 different types of waves are produced (all at the same time).
____________ waves (____ waves) – cause particles in the rocks to move back and
forth in the same direction.
- Fastest type of wave, 6.5 km/sec
ie; waves in a spring
____________ waves (____ waves) – cause rocks to move in right angles to the
direction of the wave, 3.5 km/sec
ie waves in a rope
3. Love waves or Surface waves ( ___________ )
- rock particles move in a rolling motion. Likes ripples in a pond. Slowest type of
wave
Science 10
Unit 4 – Earth Forces
Scientists have learned to use the different speeds of the waves to calculate the location of the
epicenter.
Each type of seismic wave reaches a seismograph station at a
_______________________ based upon it speed.
If seismic waves reach _____ or more stations the
________________ can be determined.
This is done by using the difference in arrival time between P
and S waves.
__________________ – the ____________ of energy waves through different layers.
Unit 4 – Earth Forces
Science 10
Unit 4.2 – Geological Time
Unit 4.2.1 – The Geological Time Scale
Handout a copy of the Geological time scale
- Breaks up the 4.6 billion years that the earth has been around into
smaller portions.
- It is categorized by rocks, fossils and other evidence.
- There are 4 divisions – ERA, PERIOD, EPOCH, TIME
Complete the worksheet
Handout pg 236, Complete pg 237
Unit 4.2.2 – Relative Dating
How do we know how old the earth is?
Scientists study the “changes”
change in volume…ex; trees, rivers, crystals
change in layers…rock layers under a river on a mountain
side or in a canyon
Relative Age or Relative Dating
– the order of the events compared to other events
Example; you fell off your bike BEFORE you got punched
by your sister
- Comparing geological events to one another. NO numbers or dates.
- Recycle bin example – the papers on the bottom must have been placed there first, unless something
moved them.
- Draw on the board some rock layers and explain oldest to youngest
- The Principle of Original Horizontality: sediments will forms layers on
top of other layers. The bottom layer must have been there first and therefore
is the oldest.
- The layers closer to the top would be the youngest. Also called The Law
of Superposition
Science 10
Unit 4 – Earth Forces
Forces with in the earth can break,
bend or disrupt the layers. Faults ,
Folds or Dikes can form.
The bold line is a fault. Layer D is called a
Dike because it cuts through the existing
layer
Is the intrusion is parallel with a layer then
it is called a sill. See letter X in the bottom
diagram.
Which layer is the oldest ? ________
Which layer is the youngest? __________
Which layer is the oldest ? _____
Which layer is the youngest?
_______________
What layer is older, B or E?
The principle of cross-cutting relationships: the intrusion is younger than
the layer is cuts through.
Ex; Y is younger than G, F, E and D
Ex; H is younger than them all except for layer ____ .
Handout page 241
Text page 263 – list the layers from youngest to oldest in diagrams c, d, e, f.
Unit 4 – Earth Forces
Science 10
Unit 4.2 – Geological Time
Unit 4.2.1 – The Geological Time Scale
Forces with in the earth can break, bend or disrupt the layers. _________ , _________
or _________ can form.
The __________________is a fault. Layer
_________ is called a _________ because it
_________ through the existing layer
Is the __________________ is
__________________with a layer then it is called a
_________. See letter X in the bottom diagram.
Which layer is the oldest ? ________
Which layer is the youngest? __________
Which layer is the oldest ? _____
Which layer is the youngest? ____
What layer is older, B or E?
The principle of __________________relationships: the intrusion is younger than
the layer is cuts through.
Ex; Y is younger than _____, _____, _____ and _____
Ex; H is younger than them all except for layer _____ .
Complete the activity in your text book page 263 – list the layers from youngest
to oldest in diagrams c, d, e, f.
Science 10
Unit 4 – Earth Forces
Unit 4.2.3 - Absolute Dating
– the time in years of each event or the actual age of the rock or fossil.
Ex; in 1993 you fell off your bike and in 1998 your
sister punched you
Ex; the rock is 235 million years old.
Geologists use radioactive decay to (half life) to calculate the age.
Example
A geologists test a rock and finds that there is a 1:7 ratio of 40K to 40Ar or
12.5% 40K and 87.5% 40Ar. If the half life of 40K is 1.3 billion years. How
old is the rock?
Video – Geological Time
Handout page 243- 245
Unit 4 – Earth Forces
Science 10
Unit 4.3 – Continental Drift
As you have learned from the first section, the outer most layer of the
earth is a thin crust and a mantle, called the lithosphere, floating on
top of a semi liquid layer called the asthenosphere. According to
plate tectonics the lithosphere moves around on the asthenosphere.
Unit 4.3.1 – The Theory of Continental Drift
If you look closely at a work map. It looks likes S. America and Africa can
fit together.
Alfred Wagner – German, thought of the theory of continental drift.
Continental drift – continents have slowly moved to their current
location
Science 10
Unit 4 – Earth Forces
Unit 4 – Earth Forces
Science 10
It is thought that at one time all of the continent were together.
The SUPERCONTENIENT
There is a lot of evidence that can prove the theory of continental
drift.
Pangea – former super continent that broke apart some 200 million
years ago.
- Formed 250 million years ago and slowly started spreading
Evidence for Continental drift:
1. Fossil evidence provide support for continental drift
Similar fossils found at similar depths in Africa and South
America. Plants and animals are only found in very specific
locations around the world.
2. Jig Saw puzzle- The large mountain ranges and coast
lines match up. Each continent has a continental shelf
Continent
Continental shelf
Ocean floor
All continental shelves are approximately 200m deep.
3. Climate clues - Fossils of warm weather plants found in
Antarctica Glacial rock in S. America and Africa. Ice ages show
the retreat of large icebergs. These icebergs leave behind deep valleys
and scratches in the ground.
There is coal in Antarctica – coal comes from decaying tropical
swamp land. If Antarctica was a swamp land then it must have been
in another location on the earth.
Unit 4 – Earth Forces
Science 10
4. Rock clues
There are rock structure that end at a coastline of a
continent and begin at another coastline in a different
continent. Rocks in Newfoundland are the same type rock
with the same age as the rocks in Norway and Sweden
Until the 1960’s scientists did not believe the theory of continental
drift because nobody could figure out how the large continents
actually moved.
During WWII the submarine was invented. It used sonar to calculate
the depth of the ocean.
Sonar - uses sound waves that echo off the ocean
floor. These sound waves are timed and the depth can
be calculated.
The researchers discovered trenches, mountains and mid ocean
ridges.
Mid ocean ridge
Continent
magma
Trench
Once the scientists researched the ocean floor they discovered 3 things
1. the rocks on the ocean floor is much younger that rocks on the
continents. 200 million vs. 3900 million years old.
2. the rock layers under the continents are much thicker than
under the ocean
3. the rocks in the ocean are much heavier than the rocks on the
continents
So what does all of this mean? How do the continents move?
Science 10
Unit 4 – Earth Forces
Unit 4.3.2 – The Theory of Plate Tectonics
Magma is released from the underwater volcanoes. This rock is very
heavy and it slowly pushes the continents away from each other. The
oceans grew from the center out. This is called sea floor spreading
Seafloor spreading
- is the theory that hot less dense material below the Earth’s
surface rises to the surface at mid ocean ridges.
- This magma then flows sideways carrying the seafloor away
from the ridge in both directions.
Evidence for Seafloor spreading
Age of rocks – youngest rocks nearest the mid ocean ridges,
increasingly older away from the ridge close to the continents.
- the patterns on both sides of the ridge are very similar
- the oceans are spreading approx. 1cm to 10cm per year
Magnetic clues – Earth’s magnetic field has a north and south pole.
This magnetic field occasionally reverses over ~500 000 years.
These reversals are recorded in the rocks formed along midocean ridges.
Particularly in rock that contain iron.
These magnetic reversals are detected with a magnetometer
Science 10
Unit 4 – Earth Forces
Handout page 249-250
They nicknamed this trend “ magnetic striping” - The proof of the stripes
finally lead to the belief that the plates move!
Science 10
Unit 4 – Earth Forces
Plate Tectonics
Sections of the seafloor and the continents move in relation to
one another
1960’s the theory of plate tectonics combined seafloor
spreading and continental drift
- believed that Earth’s crust and parts of its upper mantle
are broken into sections called plates
Plates made up of upper mantle and crust – collectively called the
lithosphere
~ 100 km thick
Plastic like layer below the lithosphere is the asthenosphere
Plates “float” on the asthenosphere
Science 10
Unit 4 – Earth Forces
Plate movement
- What causes of Plate Tectonics?
Plate movement is caused by convection current within the mantle
material
Hot, less dense mantle material is forced upward, once it reaches the
surface it cools and sinks.
Much like what happens when heating a pot of soup.
When it reaches the surface it forces the plates apart at spreading
centers, called rifts.
Plate boundaries
Areas where plates interact with each other.
When plates moving apart from each other they form a divergent
boundary
ie – seafloor spreading such as Mid-Atlantic ridge
Science 10
Unit 4 – Earth Forces
When plates move together – convergent boundary
- When an oceanic plate meets a less dense (lighter) continental
plate
- The heavier oceanic plate sinks under the continental plate.
- The area where it sinks is the subduction zone
- Can form large trenches and volcanoes
Subduction zones can also occur where 2 oceanic plates meet
New discovery – Slab Pull – the plate on the bottom actually pulls
the top plate down.
When continental plates collide there isn’t a subduction. Instead
they collide and crumple upwards forming mountains.
- Himalayas are an example
When plates slide past each other it is a transform boundary
Moving in different directions or at different speeds
- San Andreas fault in California
Handout pg 254 – 256
Questions page 257
Science 10
Unit 4 – Earth Forces
Using satellite imagery and laser technology plate movement can be
tracked.
Hawaii is moving toward Japan at a rate of 8.3 cm/ yr
Maryland is moving away from England at 1.7 cm / yr
Unit 4 – Earth Forces
Science 10
Unit 4.3 – Continental Drift
As you have learned from the first section, the outer most layer of the earth is a thin
__________ and a __________, called the _______________, floating on top of a
semi liquid layer called the _______________. According to plate tectonics the
lithosphere moves around on the asthenosphere.
Unit 4.3.1 – The Theory of Continental Drift
If you look closely at a work map. It looks likes S. America and Africa can fit together.
Alfred __________ –
German, thought of the
theory of continental drift.
_______________drift –
continents have slowly
moved to their current
location
Science 10
Unit 4 – Earth Forces
It is thought that at one time all of the continent were together.
The SUPERCONTENIENT
There is a lot of evidence that can prove the theory of continental drift.
__________ – former super continent that broke apart some 200 million years ago.
- Formed 250 million years ago and slowly started spreading
Evidence for Continental drift:
1. __________evidence provide support for continental drift
Similar fossils found at similar depths in Africa and South America. Plants and
animals are only found in _______________locations around the world.
2. _______________puzzle- The large mountain ranges and coast lines match up.
Each continent has a ____________________
Continent
Continental shelf
Ocean floor
All continental shelves are approximately 200m deep.
3. __________ clues - Fossils of warm weather plants were found in Antarctica Glacial
rock in S. America and Africa. Ice ages show the retreat of large __________. These
icebergs leave behind deep __________ and __________ in the ground.
There is __________in Antarctica – coal comes from
____________________land. If Antarctica was a swamp land then it must
have been in another location on the earth.
4. Rock clues
There are rock structure that end at a coastline of a continent and begin at another
coastline in a different continent. Rocks in Newfoundland are the same type rock with the
same age as the rocks in Norway and Sweden
Until the 1960’s scientists did not believe the theory of continental drift because nobody
could figure out how the large continents actually moved.
During WWII the submarine was invented. It used sonar to calculate the depth of the ocean.
__________ - uses sound waves that echo off the ocean floor. These
sound waves are timed and the depth can be calculated.
Science 10
The researchers discovered trenches, mountains and mid ocean ridges.
Once the
Unit 4 – Earth Forces
scientists researched the ocean floor they discovered 3 things
1. the rocks on the __________ floor are much __________ than rocks on the
__________. 200 million vs. 3900 million years old.
2. the rock layers under the continents are much thicker than under the ocean
3. the rocks in the __________ are much __________ than the rocks on the
__________
So what does all of this mean? How do the continents move?
Unit 4.3.2 – The Theory of Plate Tectonics
__________ is released from the underwater _______________. This rock is very
__________and it slowly pushes the continents away from each other. The oceans grew
from the center out. This is called ____________________
Seafloor spreading
- is the theory that ____________________ below the Earth’s surface rises to the
surface at mid ocean ridges.
- This magma then _____ _______________carrying the seafloor away from the
ridge in both directions.
Evidence for Seafloor spreading
____________________– youngest rocks nearest the mid ocean ridges, increasingly
older away from the ridge close to the continents.
a. the patterns on both sides of the ridge are very similar
b. the oceans are spreading approx. 1cm to 10cm per year
____________________– Earth’s magnetic field has a north and south pole.
This magnetic field occasionally _______________ over ~500 000 years.
These reversals are recorded in the rocks formed along mid-ocean ridges.
Particularly in rock that contain iron.
These magnetic reversals are detected with a ____________________
Science 10
Unit 4 – Earth Forces
They nicknamed this trend “ magnetic striping” - The proof of the stripes finally lead to the
belief that the plates move!
Plate Tectonics
Sections of the seafloor and the continents move in relation to one another
1960’s the theory of ____________________combined seafloor spreading and
continental drift
- believed that Earth’s crust and parts of its upper mantle are broken into sections
called plates
Science 10
Unit 4 – Earth Forces
Plates made up of upper mantle and crust – collectively called the lithosphere
~ 100 km thick
Plastic like layer below the lithosphere is the asthenosphere
Plates “float” on the asthenosphere
Plate movement
- What causes of Plate Tectonics?
Plate movement is caused by _________________________within the mantle material
_____, _______________material is forced
upward, once it reaches the surface it
_________________________.
Much like what happens when heating
a pot of soup.
When it reaches the surface it forces the plates
apart at ____________________, called
__________.
Plate boundaries
Areas where plates interact with each other.
When plates moving apart from each other they form a ________________________
ie – seafloor spreading such as Mid-Atlantic ridge
When plates move together – ______________________________
- When an oceanic plate meets a _____ _____ (lighter) continental plate
a. The heavier oceanic plate __________ under the continental plate.
b. The area where it sinks is the ____________________zone
c. Can form large __________
Subduction zones can also occur where 2 oceanic plates meet
New discovery – __________– the plate on the bottom actually pulls the top plate down.
When continental plates collide there isn’t a subduction. Instead they collide and
______________________________ forming mountains.
- Himalayas are an example
When plates slide past each other it is a ____________________ boundary
Moving in different directions or at different speeds
- San Andreas fault in California
Science 10
Unit 4 – Earth Forces
Using satellite imagery and laser technology plate movement can be tracked.
Hawaii is moving toward Japan at a rate of 8.3 cm/ yr
Maryland is moving away from England at 1.7 cm / yr
Science 10
Unit 4 – Earth Forces
Unit 4.4 – Volcanoes
Over 80 % of Earth’s surface, including portions of the ocean, is of
volcanic origin.
- A Volcano is an opening in the Earth’s surface that erupts
gases, ash and lava.
Volcanic mountains form when lava, ash and other material build up
around these openings.
There are approx 600 active volcanoes and 75% of them are in the
“Ring of Fire”
3 types of volcanoes
1. Composite
a. Classic shape
b. Formed from hot bits of rock that has been hurled up from
the crust to form a new layer on the side of the volcano.
c. Lava can flow or burst (explode) out of the top, it is very
thick, cools and creates another layer (strata), the volcano
will grow in size.
d. Forms at SUBDUCTION zones
2. Shield
a. Very wide and low base
b. Lava flows out of many spots and is very fluid
c. Can be very gentle
d. Form at HOT SPOTS – weak spot in the lithosphere where
magma can get through
e. All of the Hawaiian and Galapagos Islands were formed by
shield volcanoes
There is a shield volcano on Mars that is 25Km high!
Science 10
Unit 4 – Earth Forces
3. Rift Volcanoes
a. Occur at spreading ridges in the ocean or on land
b. lava flows out of fissures (or cracks) in the crust
c. not violent, but can release a lot of lava.
The Columbian River Plateau, from Canada through Washington and
Oregon into California is a rift volcano. 30 million years old.
Impact of Valcnoes
The ash, gas and debris that explode out of the top or rush down the
sides of a volcano is called pyroclastic flow.
- Can move at speeds of up to 300 km/hr – they actually ride on
a cushion of air.
- is superheated to 1000oC
- Responsible for most of the loss of life and damage to
property caused by volcanoes in the 20th century
Science 10
Unit 4 – Earth Forces
Lahar - if a volcano erupts that is covered in snow and ice, the snow
and ice will melt and wash down the sides of the volcano with all of
the mud and debris.
In 1985, in Columbia, a volcano erupted and the lahar buried a town
100km away in 4 hr with 5 meters deep of mud and debris. 23 people
died, the mud was like concrete and hardened quickly.
Ash can go 10 km high, and be carried around the world.
In 1815, a volcano in India, released so much ash that it block the sun
for months. It caused the earths temperature to drop dramatically.
Major famines occurred because crops could not grow due to the frost
in JULY.
How do volcanoes form?
Deep inside the earth heat and pressure cause rock to melt forming
magma.
Magma is less dense than the rock around it, so it is slowly forced to
the earth’s surface.
After thousands to
millions of years the
magma flows out of an
opening in called a vent.
As lava flows out it cools
and forms igneous rocks,
over time several layers
can form.
The steep walled
depression around the
Science 10
volcanoes vent is called a crater.
Unit 4 – Earth Forces
Science 10
Unit 4 – Earth Forces
Where are volcanoes Located?
Most volcanoes form along the edges of the earth’s plates, where magma comes up where
the earth’s crust is broken.
At convergent boundaries volcanoes are common
Magma forms when the plate sliding below another plate and the
overlying plate partially melt.
Science 10
Ex; Mount St. Helens- Composite Volcano
Unit 4 – Earth Forces
Science 10
Unit 4 – Earth Forces
- The largest landslide in recorded history swept down the mountain
at speeds of 150 miles per hour and buried the Toutle River under an
average of 150 feet of debris.
 MSH was 9,677 feet before the eruption and 8,363 feet after. 1,314
feet was removed by the May 18th eruption
 Some areas are covered by as much as 600 feet.
 The lateral blast swept out of the north side of MSH at 300 miles
per hour creating a 230 square mile fan shaped area of devastation
reaching a distance of 17 miles from the crater.
 Temperatures as high as 660 OF and the power of 24 megatons of
thermal energy, it snapped 100 year old trees like toothpicks and
stripped them of their bark.
 Pyroclastic flows rolled out of the crater for 9 hours after the
eruption. Covering 6 square miles they sterilized the remaining
soil with temperatures nearing 1,300 OF.
 The massive ash cloud grew to 80,000 feet (18 kilometers) in 15
minutes and reached the east coast in 3 days. Although most of the
ash fell within 300 miles of the mountain finer ash circled the earth
in 15 days and may continue to stay in the atmosphere for many
years.

The lava dome rises 876 feet above the crater floor and is about
3,500 feet in diameter.
Video – Predicting Earthquakes and Volcanoes – (23min) VT551.2 P9221
Unit 4 – Earth Forces
Science 10
Unit 4.4 – Volcanoes
Over 80 % of Earth’s surface, including portions of the ocean, is of volcanic origin.
-
A ________ is an opening in the Earth’s surface that erupts ________,
________and ________.
Volcanic mountains form when lava, ash and other material build up around these openings.
There are approx 600 active volcanoes and 75% of them are in the “________________”
3 types of volcanoes
1. ________________
a. ________ shape
b. Formed from hot bits of rock that has been hurled up from the crust to form a
new ________ on the ________ of the volcano.
c. Lava can flow or ________ (explode) out of the top, it is
_______________, ________ and creates another layer (________),
the volcano will grow in size.
d. Forms at ________________ zones
2. Shield
a. Very ________ and ________ base
b. Lava ________ out of many spots and is very ________
c. Can be very ________
d. Form at ________________– weak spot in the lithosphere where magma
can get through
e. All of the Hawaiian and Galapagos Islands were formed by _______volcanoes
There is a shield volcano on Mars that is 25Km high!
3. ________Volcanoes
a. Occur at ________________________in the ocean or on land
b. lava flows out of ________ (or cracks) in the crust
c. not violent, but can release a lot of lava.
The Columbian River Plateau, from Canada through Washington and Oregon into California
is a rift volcano. 30 million years old.
Science 10
Impact of Valcnoes
Unit 4 – Earth Forces
The ________, ________ and ________ that explode out of the top or rush down the
sides of a volcano is called ________________________.
- Can move at speeds of up to 300 km/hr – they actually ride on a cushion of air.
- is superheated to ________
- Responsible for most of the loss of life and damage to property caused by volcanoes
in the 20th century
__________ - if a volcano erupts that is covered in
________ and ________, the snow and ice will melt
and wash down the sides of the volcano with all of the
________ and __________.
In 1985, in Columbia, a volcano erupted and the
lahar buried a town 100km away in 4 hr with 5 meters
deep of mud and debris. 23 people died, the mud
was like concrete and hardened quickly.
Ash can go 10 km high, and be carried around the world.
In 1815, a volcano in India, released so much ash that it block the sun for months. It caused
the earths temperature to drop dramatically. Major famines occurred because crops could
not grow due to the frost in JULY.
How do volcanoes form?
Deep inside the earth heat and pressure cause _______
_______________________________________.
Magma is _______ ________ than the rock around it,
so it is slowly forced to the earth’s surface.
After thousands to millions of years the magma flows out
of an opening in called a ________.
As lava flows out it _________ and forms _________
rocks, over time several layers can form.
The steep walled depression around the volcanoes vent is
called a __________.
Science 10
Unit 4 – Earth Forces
Where are volcanoes Located?
Most volcanoes form along the edges of the earth’s plates, where magma comes up where
the earth’s crust is broken.
At _____________________________ volcanoes are common
Magma forms when the plate sliding below another plate and the overlying plate
partially melt.